Nemanja Vidic insists Manchester United have no intention of letting lightning strike twice even though they still have some tricky hurdles to navigate before they reaching the Premier League winning line.

At the end of Cheltenham week, as the Red Devils extended their lead to 15 points with a 1-0 home win over Reading, keen racing enthusiast Sir Alex Ferguson embraced the theory that a testing run-in can catch even the most likely winners out, as it would take a collapse even more shocking than Devon Loch in the 1956 Grand National to deprive United of a record 20th title.

But Vidic is still preaching caution, and he said: "It is a big gap and we shouldn't let that change. We have the title in our hands. What happened last season is the reason why sometimes you can feel the fans get nervous. But I don't think we should allow that to happen again. We can't allow that to happen again."

He added: "But we still have some tough away games at places that are traditionally hard for us so nothing is finished yet."

It is true that Manchester City, Arsenal and Chelsea represent a third of their remaining fixtures.

But Aston Villa and Swansea must go to Old Trafford too, which should account for almost half of the 13 points now required after Wayne Rooney's 16th goal of the season wrapped up a 1-0 win against Reading.

And the memory of that journey back from Sunderland last season, after City's late heroics had snatched away a prize they finished their final game believing was going to be theirs is likely to ensure no loss of focus.

"You don't get any points for that," said Ferguson, when asked if United would be counting their chickens.

Defender Chris Smalling was more measured in his response.

"Last season is a massive incentive to make sure we hold on to this lead," he said. "We can't rest on our laurels. We have to make sure we finish it well before the season is over."